On the propagation of two types of disturbances through a laminar boundary layer subjected to separation and transition

Irps, Thomas J B and Kanjirakkad, Vasudevan (2022) On the propagation of two types of disturbances through a laminar boundary layer subjected to separation and transition. In: Sherwin, Spencer, Schmid, Peter and Wu, Xuesong (eds.) IUTAM laminar-turbulent transition: 9th IUTAM symposium, London, UK, September 2–6, 2019. IUTAM Bookseries, 38 . Springer, Cham, pp. 407-418. ISBN 9783030679019

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The propagation of two types of artificial disturbances within a boundary layer is discussed. The boundary layer is initially laminar but later transitions to become turbulent through the formation of a separation bubble under the influence of an imposed adverse pressure gradient. The growth of the boundary layer and that of the disturbances within it are tracked experimentally using hotwire anemometry measurements. The effects of the interaction of the disturbances with the separation bubble are captured using both hotwire and particle image velocimetry measurements. For a chord based Reynolds number of 210 k it is shown that Kelvin–Helmholtz shedding frequencies over the bubble are unchanged in the presence of either of the disturbances and are comparable to the steady flow case with no disturbances present. Both disturbances produced an extensive calmed region on interacting with the bubble. The calmed region due to the bar wake is relatively longer and persistent. The upstream location of the separation bubble formation is unaffected by the disturbances, however the average size of the bubble is shown to be sensitive to the type of disturbance with the bar wake producing a thinner and shorter bubble.

Item Type: Book Section
Keywords: Laminar-Turbulent transition, Separated Boundary Layer, Separation Bubble, Tollmien–Schlichting wave, Kelvin–Helmholtz instability
Research Centres and Groups: Thermo-Fluid Mechanics Research Centre
SWORD Depositor: Mx Elements Account
Depositing User: Mx Elements Account
Date Deposited: 31 Aug 2021 12:45
Last Modified: 01 Aug 2022 01:00
URI: http://sro.sussex.ac.uk/id/eprint/101373

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